Systems and devices for urinalysis are extensively used and practiced in clinics, laboratories and the like. With the increased presence of infectious diseases, such as AIDS, in biological materials, the need for safe systems and devices to minimize the handling of these potentially dangerous substances becomes evident. Urine sediment examination typically involves, as described in the U.S. Pat. Nos. 4,393,466 and 4,612,614, pouring of a sample into a tube which is then spun in a centrifuge to separate the sediment from its suspending fluid. After centrifugation, the cleared suspending fluid is poured out and the sediment resuspended in the remaining fluid. A sample of the resuspended sample must then be transferred to a microscopic slide for examination with a microscope. The '466 patent further describes a technique with which manual urine handling steps are eliminated and a video system is used to provide an electronic image of the urine specimen. A slide assembly is described which is shaped to provide a stable sample area where solid particles in the urine sample can be viewed.
Various other types of urine or other fluid sample supply devices are shown and described in the art, see for example, U.S. Pat. Nos. 4,302,421, 4,312,591, 4,367,043, 4,448,752, 4,836,038, 3,948,607, 4,209,256, and 4,271,123.
U.S. Pat. No. 4,804,267 to Walter Greenfield describes a urine sample analyzing system. A peristaltic pump is used to alternately pull a urine sample or a flushing fluid through a slide assembly, also known as a flow cell. A video display system is employed to investigate solids in the sample.
Problems encountered with conventional slide assemblies may involve too great a thickness of the test specimen so that the microscope, which usually has a very short focal length, tends to be focused at different focal planes of the test specimen. When the flow cell is made with plastic components through which either the microscope views the test sample or through which illuminating light passes, distortions tend to appear in the field of view of the microscope. Frequently, cement may be used to attach flow cell components and this cement tends to be attacked by constituents in the urine and some cleaning fluids over extended uses leading to a disintegration of the slide assembly. Cement also tends to have tiny edges to which various undesirable contaminants become attached such as bacteria, molds, yeast and particles and are not readily dislodged by a flushing cycle. When the passageway into the viewing chamber of the slide assembly has relatively abrupt turns, tiny bubbles tend to form and are entrained into the viewing chamber where they obscure or confuse the clarity of the field of view of the microscope. Where cement/plastic plexiglass interfaces are exposed to air and heat from the condensed light source, dust particles are attracted and appear as other urine constituents such as bacteria, yeast, fibers, and mucus to the microscope operator when these interfaces also appear in the field of view.
It is important that slide assemblies are sufficiently thin to enable mounting to any microscope without interference with different lenses of a microscope turret. It is also desirable that a slide assembly be useful with a variety of microscopic techniques such as the one commonly known as "bright field" and other techniques generally referred to as Hoffman modulation, phase contrast, polarized light and fluorescence. It is furthermore desirable that a relatively small amount of test fluid is used to fill a viewing chamber of a slide assembly so that more than one examination can be made with the same test fluid.
The various known urinalysis systems tend to be complex and do not provide an inexpensive and convenient approach to the handling of urinalysis in laboratories where complex fully automated systems cannot easily, economically be justified.
In the evaluation of urine, it is at first necessary to concentrate the solids in a centrifuge operation, but then the solids should be resuspended. In order to achieve a reasonably consistent basis for analysis, the resuspension preferably should be carried out with the same volume of urine.
Various collection tubes have been proposed for extracting, separating or otherwise segregating components from a body fluid. For example, U.S. Pat. No. 3,818,248 describes a collection tube with which different phases of a fluid are separated. The device includes a movable sealing element or "traveling spool" which divides a test tube into an upper chamber and a lower chamber which has a floating plug. This device can serve the function described but does not permit the collection of a fixed or constant volume or urine.
U.S. Pat. No. 4,824,560 describes a urine centrifuge tube containing a partition that is shaped to promote the collection of solids in a lower chamber during centrifuge. The partition is pierced by a bore whose cross-section is less than 10 mm. and preferably not more than 5 mm. and is described even as a capillary bore. Even though the tube can yield a collection of solids in a lower chamber, during the decanting of excess liquid from the upper chamber, liquid from the lower chamber would tend to escape as well. This is particularly a problem with larger bore sizes while with a capillary bore, it is difficult to remove a consistent sample. Furthermore, no device is shown to facilitate the break-up for resuspension of consolidated solids.
Other body liquid collection tubes, some for centrifuge operations, are described in U.S. Pat. Nos. 4,464,254, 4,308,028, 4,055,501, 3,935,113, 3,945,928, and 3,849,072. These patents describe devices with similar drawbacks.